Atmosphere and its Structure: Our earth is surrounded by a vast envelope of air known as the Atmosphere. It is held to the earth’s surface by its gravity. The air is composed of tiny molecules of gases. A molecule is the smallest particle of a substance. These molecules move randomly in all directions in the air. The number of molecules present in a unit/volume determines the density of air. The number of molecules present in the air is very high near the surface of the earth. Therefore, the density of the atmosphere is high near the surface. As we go … Continue reading Atmosphere and its Structure: